CMMG Banshee Mk4 338 ARC Armor Black 10.5 in. – Rugged AR Pistol

Description

The CMMG Banshee Mk4 338 ARC Armor Black is a compact AR-15 pattern pistol built around Hornady’s 338 ARC, a big-bore cartridge designed to deliver heavy bullets from short barrels. It pairs a 10.5-inch barrel with an adjustable gas block, a ZEROED brake and CMMG’s arm brace in an Armor Black Cerakote finish.

CMMG Banshee Mk4 338 ARC Armor Black Overview

The 338 ARC was introduced by Hornady as a short-range thumper for the AR-15 platform, aimed squarely at shooters who want energy similar to a 30-30 or better in a compact package, with optional quiet loads for suppressor use. CMMG’s Banshee line is its family of short AR pistols, and this Mk4 version keeps the standard AR-15 manual of arms, with a buffer-tube rear end, an ambidextrous ZEROED charging handle and familiar lower controls. 56 pistol of the same size.

338 ARC Ballistics and Ammo

Hornady offers supersonic 170 grain MonoFlex and heavier 215 grain FTX loads, plus a 300 grain subsonic load intended for suppressed rifles. Heavy, wide bullets make this a sensible choice for hogs and deer at moderate ranges. The trade-off is cost and selection: 338 ARC is new, only a handful of factory loads exist, and per-round prices are well above 5.56 or 300 Blackout. Buy ammunition before you need it.

Barrel, Gas and Muzzle Brake

The 10.5 inch medium-taper barrel is 4140 chrome moly with a nitride finish and a 1:8 twist, threaded 5/8×24 to suit 30 and 338 caliber muzzle devices. A pistol-length gas system with an adjustable .750 gas block lets you tune for supersonic or quiet loads. The ZEROED SVB brake tames recoil but is very loud and concussive from a short barrel, especially indoors or next to other shooters. Suppressors are NFA items requiring an approved ATF Form 4 and state legality.

Brace, Handguard and Controls

The Banshee wears the CMMG RipBrace, an arm brace intended to stabilize the pistol against the forearm. Brace rules have changed several times; the 2023 ATF brace rule was struck down in court, but you should confirm current federal guidance and your state rules before configuring any braced pistol. The EML9 M-LOK handguard has room for a light and a hand stop, and the billet 6061 upper sits on a forged 7075 lower.

Magazine Note

CMMG lists one 10-round CMMG 338 ARC magazine in the box, while some distributor listings describe a 30-round magazine. Treat the exact magazine count as unconfirmed and plan to buy spares. Because the 338 ARC case is fat, capacity in a standard AR-15 sized magazine is lower than with 5.56, so check magazine compatibility carefully before buying aftermarket options.

Shooting Experience and Ownership

Expect noticeably more recoil and blast than a 5.56 Banshee, though the brake helps. A red dot or low-power optic suits the cartridge’s effective range. CMMG backs its products with a lifetime quality guarantee, and Armor Black Cerakote is tough and easy to clean. Resale value is solid for a CMMG, but demand for 338 ARC guns depends on how widely the cartridge catches on.

State Laws and Ownership

AR pistols are restricted or banned in several states, including California, New York, New Jersey, Connecticut, Maryland, Massachusetts, Washington, Illinois and Colorado. Some states regulate threaded barrels, braces or magazine capacity separately. Local laws can add more limits. Confirm that this pistol can be legally transferred to you before ordering.

Specifications

• Manufacturer: CMMG
• Model: Banshee Mk4, part 34A390F-AB
• Caliber: 338 ARC
• Operation: Direct impingement, pistol-length gas
• Barrel: 10.5 inch, 4140CM nitride, 1:8 twist, 5/8×24
• Muzzle device: ZEROED SVB brake
• Gas block: Adjustable .750
• Upper: Mk4 billet 6061 T6; Lower: Mk4 forged 7075 T6
• Handguard: EML9 M-LOK
• Charging handle: CMMG ZEROED ambi
• Brace: CMMG arm brace
• Magazine: 10-round per CMMG (see note)
• Weight: 5.6 lb
• Overall length: 26 inch
• Finish: Armor Black Cerakote
• UPC: 840442506582

Before You Buy

Federal law requires this handgun to ship to a licensed FFL dealer for transfer with Form 4473 and a background check, and handgun buyers must be 21 or older to purchase from a dealer. Verify brace and pistol rules in your state and plan your ammunition supply.

Who It Is For

The CMMG Banshee Mk4 338 ARC Armor Black is a great fit for hog hunters, ranchers and home owners who want a compact AR pistol that hits harder than 5.56, and shooters planning a future suppressed big-bore build.

Buy the CMMG Banshee Mk4 338 ARC Armor Black at MAG5 Firearms

MAG5 Firearms is a family-owned FFL in Collegeville, Pennsylvania. Order the CMMG Banshee Mk4 338 ARC Armor Black online and ship it to your local FFL dealer, or browse our full selection of firearms for more pistols. For factory details, visit CMMG.